Packing assembly for cylinder casing

ABSTRACT

A packing assembly for a cylinder is clamped between two parts of a casing of a cylinder between which a piston is received. The piston has a shaft which extends out from the casing of the cylinder. The packing assembly includes two seal frames connected to the two parts and the packing is clamped between the two seal frames. The packing includes a seal portion in contact with a top and a bottom of the piston. A seal tongue extends from the inner periphery of the packing and is in contact with inside of the two parts so as to seal the conjunction portion of the two parts of the casing. The seal frames are tightly engaged with the two parts of the cylinder so that the two respective connection peripheries of the two parts do not need to be machined precisely.

FIELD OF THE INVENTION

The present invention relates to a packing assembly which includes two packing frames with a packing clamped therebetween, so that the connection periphery of two parts of the cylinder casing need not to be precisely machined.

BACKGROUND OF THE INVENTION

A conventional cylinder is shown in FIGS. 5 to 7 and generally includes a fan-shaped piston 10 which is received in a casing composed of two half parts 12 and a packing 11 is clamped between the two parts 12 so as to achieve an air sealed combination. One of the two parts 12 has an inlet 121 for introduction of air and the other part 12 has an outlet (not shown) to allow air to escape therefrom when the fan-shaped piston 10 is pivoted about a shaft 101 between the two parts 12. The packing 11 is an enclosed member and includes a flexible portion 112 extending from an inner periphery thereof. The flexible portion 112 are in contact with top and bottom of the fan-shaped piston 10 so as to have a sealed function when the piston 10 is operated. Nevertheless, the packing 10 clamped between the two parts 12 is affected and/or deformed by the temperature change so that leakage happens from gaps between the packing 11 and the two parts 12. In order to well position the packing 11, the connection periphery of each of the two parts 12 has to be provided with a groove which is machined precisely to accommodate the packing 11. The parts 12 are made by metal so that complex processes are required to make the grooves in the limited area of the connection periphery. Once the groove is not machined precisely, leakage happens.

The present invention intends to provide a packing assembly that includes two packing frames which are easily matched with the parts and the packing is clamped between the tow frames which are engaged with the two parts. The packing includes a seal tongue to contact the insides of the two seal frames so as to prevent leakage between the packing and the half parts of the casing.

SUMMARY OF THE INVENTION

The present invention relates to a cylinder which includes a casing composed of two parts and a piston is received between the two parts so as to drive a shaft extending out from the cylinder. Two seal frames are engaged with two respective insides of the two parts and a packing is clamped between the two seal frame. A seal portion extends from an inner periphery of the packing and is in contact with a top and a bottom of the piston. A seal tongue extends from the inner periphery of the packing and is in contact with two respective insides of the two parts.

The primary object of the present invention is to provide a packing assembly that is easily positioned between the two parts of the cylinder without precisely machining processes to the two parts of the casing.

The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cylinder with the packing assembly of the present invention;

FIG. 2 is an exploded view to show the cylinder with the packing assembly of the present invention;

FIG. 3 is a cross sectional view to show the packing assembly in the cylinder;

FIG. 4 is an enlarged cross sectional view to show that the seal tongue of the packing contacting the insides of the two parts;

FIG. 5 is an exploded view to show a conventional packing and cylinder;

FIG. 6 is a cross sectional view to show the conventional packing in the casing of the cylinder, and

FIG. 7 is an enlarged cross sectional view to show that the conventional packing cannot prevent leakage from the conjunction portion of the two parts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 to 4, the packing assembly of the present invention is clamped between two parts 12 of a casing of the cylinder 1 and a fan-shaped piston 10 is received between the two parts 12. One of the two parts 12 has an inlet 121 for introducing air in the cylinder 1 and the other part 12 has an outlet (not shown) to allow air to escape from the cylinder 1. The piston 10 has a shaft 101 which extends out from the cylinder so as to output torque.

The packing assembly includes two seal frames 13 engaged with two respective insides of the two parts 12 and a packing 11 clamped between the two seal frame 13, a seal portion 112 extending from an inner periphery of the packing 11 and being in contact with a top and a bottom of the piston 10, a seal tongue 111 extending from the inner periphery of the packing 11 and in contact with two respective insides of the two parts 12.

The packing 11 includes two ring-shaped portions 112 connected on two facing insides of the packing 11. The two ring-shaped portions 112 are in contact with a top and a bottom of the piston 10. A seal tongue 111 extends from each of the ring-shaped portions 112 and is in contact with inside of the two parts 12. The seal tongues 111 made by flexible material and in a loop shape which extends inclinedly outward from the ring-shaped portion 112.

When the fan-shaped piston 10 is pivoted about the shaft 101, the ring-shaped portions 112 seal the top and bottom of the fan-shaped piston 10 and the tongues 111 seal the conjunction portion of the two parts 12. As shown in FIG. 5, even if the packing 11 is deformed due to temperature change, the flexible tongues 111 of the packing 11 are still in contact with the insides of the two parts 12 such that leakage can be efficiently prevented.

While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention. 

1. A cylinder 1 comprising: a casing composed of two parts 12 and a piston 10 received between the two parts 12, the piston 10 having a shaft 101 which extends out from the cylinder 1, two seal frames 13 engaged with two respective insides of the two parts 12 and a packing 11 clamped between the two seal frame 13, a seal portion 112 extending from an inner periphery of the packing 11 and being in contact with a top and a bottom of the piston 10, a seal tongue 111 extending from the inner periphery of the packing 11 and in contact with two respective insides of the two parts
 12. 2. The cylinder as claimed in claim 1, wherein the seal tongue 111 extends inclinedly outward from the inner periphery of the packing
 11. 3. The cylinder as claimed in claim 1, wherein the seal tongue 111 is made by flexible material. 